Modelling, analysis and optimization of adsorption parameters for H3PO4 activated rubber wood sawdust using response surface methodology (RSM).

Adsorption capacity of Cu(2+) from aqueous solution onto H(3)PO(4) activated carbon using rubber wood sawdust (RSAC) was investigated in a batch system. Kinetic and isotherm studies were carried out, the thermodynamic parameters like standard Gibb's free energy (Delta G degrees), enthalpy (Delta H degrees) and entropy (DeltaS degrees) were evaluated. The pseudo-second-order model was found to explain the kinetics of Cu(2+) adsorption most effectively. The process optimization was performed through Central Composite Rotary Design using response surface methodology (RSM) by Design Expert Version 5.0.7 (STAT-EASE Inc., Minneapolis, USA). An initial concentration of 35 mg L(-1), temperature of 26 degrees C, carbon loading of 0.45 g(100mL)(-1), adsorption time 208 min and pH of 6.5 was found to be the optimum conditions for the maximum uptake of copper ions of 5.6 mg g(-1) in batch mode.